airway [Gk, aer + AS, weg, way] , 1. a tubular passage for movement of air into and out of the lung. An airway with a diameter greater than 2 mm is defined as a large, or central, airway such as a mainstream bronchus; one smaller than 2 mm is considered a small, or peripheral, airway such as a terminal bronchus. 2. a respiratory anesthesia device. 3. an oropharyngeal tube used for mouth-to-mouth resuscitation.